Narrative:

Much of the winter here there is snow; ice; or a combination of the two covering ramps; txwys; and runways. However; it is relatively rare that this contamination precludes operations for most aircraft; and I have taxied; taken off; landed many times with runway contamination once it's been determined that it's safe to do so. On the morning of departure; there had been about 1 inch of fresh snow on top of all paved surfaces that had been cleared the day prior; which usually gives improved (and good) traction. I drove a good portion of the ramp area; taxiway and runway in my car to test traction and braking and found both to be good. Brakes held fine during run-up; and aircraft did not slide or give any other indication of reduced traction during taxi into position on the runway. During warm-up and taxi out; a thin layer (very thin fog with blue sky visible directly above) of reduced visibility moved in; although ASOS continued to report 10 mi visibility; 1700 ft overcast. As aircraft accelerated during the takeoff roll; however; the layer began visually to merge with the snow on the runway and the snow to the side; causing me considerable difficulty in perceiving the runway edges at increased speed. Since no pavement was visible; I used the marker poles that were placed at intervals to the inside of the snow banks to keep the aircraft centered on the runway. The combination of flat light and white on both runway surface and edges gave me the impression of being well within the plowed edges when in fact the aircraft had slid to the left of centerline. The left main contacted heavier snow at the edge of cleared runway which quickly and unctlably pulled the aircraft to the left and into the snow bank. A contributing factor; it turns out; was that I had assumed the entire runway had good traction from the roughly 1/3 (2000+ ft) that I drove in my car to test it but in fact there was an ice layer concealed by the snow that had persisted in the middle area of the runway. I would recommend that once winter plowing commences airports in snow country NOTAM the effective width of the runway; which is reduced even when plowed to the edges (snow banks can cause conflict with wings). I would also recommend that highly visible; reflective markers be placed at regular intervals in the snow bank; perhaps co-located with lights. Finally; I recommend that traction tests done with test vehicles extend over the entire length of the runway; not just the landing and takeoff zones; as braking action can vary significantly over the runway length.

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Original NASA ASRS Text

Title: BE58 PILOT DRIFTS INTO SNOW BANK DURING TKOF AT UNCONTROLLED ARPT DUE TO ICY CONDITIONS AND POOR VISIBILITY.

Narrative: MUCH OF THE WINTER HERE THERE IS SNOW; ICE; OR A COMBINATION OF THE TWO COVERING RAMPS; TXWYS; AND RWYS. HOWEVER; IT IS RELATIVELY RARE THAT THIS CONTAMINATION PRECLUDES OPS FOR MOST ACFT; AND I HAVE TAXIED; TAKEN OFF; LANDED MANY TIMES WITH RWY CONTAMINATION ONCE IT'S BEEN DETERMINED THAT IT'S SAFE TO DO SO. ON THE MORNING OF DEP; THERE HAD BEEN ABOUT 1 INCH OF FRESH SNOW ON TOP OF ALL PAVED SURFACES THAT HAD BEEN CLRED THE DAY PRIOR; WHICH USUALLY GIVES IMPROVED (AND GOOD) TRACTION. I DROVE A GOOD PORTION OF THE RAMP AREA; TXWY AND RWY IN MY CAR TO TEST TRACTION AND BRAKING AND FOUND BOTH TO BE GOOD. BRAKES HELD FINE DURING RUN-UP; AND ACFT DID NOT SLIDE OR GIVE ANY OTHER INDICATION OF REDUCED TRACTION DURING TAXI INTO POS ON THE RWY. DURING WARM-UP AND TAXI OUT; A THIN LAYER (VERY THIN FOG WITH BLUE SKY VISIBLE DIRECTLY ABOVE) OF REDUCED VISIBILITY MOVED IN; ALTHOUGH ASOS CONTINUED TO RPT 10 MI VISIBILITY; 1700 FT OVCST. AS ACFT ACCELERATED DURING THE TKOF ROLL; HOWEVER; THE LAYER BEGAN VISUALLY TO MERGE WITH THE SNOW ON THE RWY AND THE SNOW TO THE SIDE; CAUSING ME CONSIDERABLE DIFFICULTY IN PERCEIVING THE RWY EDGES AT INCREASED SPD. SINCE NO PAVEMENT WAS VISIBLE; I USED THE MARKER POLES THAT WERE PLACED AT INTERVALS TO THE INSIDE OF THE SNOW BANKS TO KEEP THE ACFT CTRED ON THE RWY. THE COMBINATION OF FLAT LIGHT AND WHITE ON BOTH RWY SURFACE AND EDGES GAVE ME THE IMPRESSION OF BEING WELL WITHIN THE PLOWED EDGES WHEN IN FACT THE ACFT HAD SLID TO THE L OF CTRLINE. THE L MAIN CONTACTED HEAVIER SNOW AT THE EDGE OF CLRED RWY WHICH QUICKLY AND UNCTLABLY PULLED THE ACFT TO THE L AND INTO THE SNOW BANK. A CONTRIBUTING FACTOR; IT TURNS OUT; WAS THAT I HAD ASSUMED THE ENTIRE RWY HAD GOOD TRACTION FROM THE ROUGHLY 1/3 (2000+ FT) THAT I DROVE IN MY CAR TO TEST IT BUT IN FACT THERE WAS AN ICE LAYER CONCEALED BY THE SNOW THAT HAD PERSISTED IN THE MIDDLE AREA OF THE RWY. I WOULD RECOMMEND THAT ONCE WINTER PLOWING COMMENCES ARPTS IN SNOW COUNTRY NOTAM THE EFFECTIVE WIDTH OF THE RWY; WHICH IS REDUCED EVEN WHEN PLOWED TO THE EDGES (SNOW BANKS CAN CAUSE CONFLICT WITH WINGS). I WOULD ALSO RECOMMEND THAT HIGHLY VISIBLE; REFLECTIVE MARKERS BE PLACED AT REGULAR INTERVALS IN THE SNOW BANK; PERHAPS CO-LOCATED WITH LIGHTS. FINALLY; I RECOMMEND THAT TRACTION TESTS DONE WITH TEST VEHICLES EXTEND OVER THE ENTIRE LENGTH OF THE RWY; NOT JUST THE LNDG AND TKOF ZONES; AS BRAKING ACTION CAN VARY SIGNIFICANTLY OVER THE RWY LENGTH.

Data retrieved from NASA's ASRS site as of May 2009 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.